1. Field of the Invention
This particular invention, in general, pertains to a foam forming and delivery system and method. More specifically, it is directed to a simple, inexpensive, compact, and highly reliable system and process for ensuring accuracy and consistency in metering, mixing and delivering the constituent materials which form foam as well as improving the application thereof under adverse temperature conditions.
2. Description of the Prior Art
Heretofore several prior art attempts have been undertaken in the foam applicating field in an attempt to effectively and efficiently form and apply foam to appropriate working areas. Typically, such foam material may be utilized for purposes of providing thermal and/or acoustical insulation barriers which are particularly useful in the building and construction field. The very nature of the construction and building industry is such that ordinarily the foam applying procedure must occur at widely differing locations.
Generally speaking, the standard operating procedure for producing this type of foam encompasses pumping curable synthetic resinous material and a foaming agent with pressurized fluid individually from large separate drums into a suitable mixing gun. Additionally, pressurized fluid, such as air, from a conventional air compressor or the like is directed to the gun for purposes of mixing with the resinous agent and the foaming agent so as to form the foam product. The mixing gun suitably mixes and dispenses the formed foamed material.
One considerable problem commonly encountered in effectively operating such a system is ensuring a proper and continuous mixing of the desired quantities of the constituent ingredients which form the foam. If the correct preselected ratio of ingredients is not consistently delivered to the mixing point, the foam may not form. In many instances if the foam does form, it will not be of the proper composition and therefore will be unsatisfactory for the intended purposes. For instance, if formed at all, defects will arise in the final product, such as material streaking, excessive water loss, foam decomposition, and noxious odors. It is extremely important to ensure that the preselected mixing ratio during foam formation is consistently met and maintained, otherwise a very unsatisfactory product will result.
Given the fact that the mixing gun may be separated from the material containing drums by considerable distances, another problem which resides in this prior art system is that very significant pumping forces are required to successfully transfer the material to the mixing gun while maintaining the requisite pressures of the gun. Thus, pumping the materials under consistent conditions over large distances has, in the past, also contributed to the production of defective foam products.
Earlier approaches in pumping the foaming agent and curable synthetic resinous materials to the foam mixing gun included the use of pressure vats or chambers. Such vats usually received charges of the appropriate material to be transferred and were suitably pressurized so as to force the material to the mixing gun. A particular disadvantage associated with the foregoing arrangement was that the vats were often large and bulky. This very cumbersome characteristic was a great drawback at on-site job locations. Moreover, with the advent of relatively stringent federal standards concerning occupational safety hazards, these types of pressure vats had to be reconstructed so as to be even larger, heavier and sturdier. This rendered them even less acceptable and less suitable for commercial use not only from a cost standpoint but, in addition, from a handling standpoint. The foregoing shortcomings were compounded by the fact that the vats would have to be refilled after each charge of material was dispensed.
Another prior art approach for on-site application of foam involved a conventional type of vertical pneumatic displacement piston pump in combination with material supply drums and a mixing gun. In the customary arrangement, these pumps are positioned within the standard material supply drums to pump the materials under suitable pressure. This system had, inter alia, a significant shortcoming in that the repeated reversal of the piston direction resulted in fluid pressure cycling and fluctuations during the pumping of the materials. The considerable adverse effects accompanying these pressure fluctuations resulted in the innaccurate proportional mixing of the foaming agent and curable synthetic materials. Thus, there was no assurance that the curable synthetic resin and foaming agent material would be delivered to the mixing gun in the predetermined volumes or quantities desired for producing the foam product of choice.
To achieve a successful production of insulating and/or acoustical foam material, the various constituent materials, including the curable synthetic resin and foaming agent, must be continually mixed together in the proper predetermined amounts. Otherwise, the finished foam product, if formed at all, would lack the uniformity and consistency necessary to meet the building specifications for products of this type. For instance, when the pumping is inconsistent, it is not uncommon to have the foam material components streak during discharge from the gun, with the result that incorrect amounts of the ingredients would be mixed. Other adverse results associated with such inconsistencies are that the foam would not set-up properly and in many instances, would eventually collapse. Moreover, when the foam actually is collapsed, there is the additional drawback caused by the creation of noxious odors. This latter result is especially detrimental since the foam is customarily applied in buildings where occupants would be affected.
As noted, the reasons for pressure fluctuations with such type of pneumatic vertical displacement piston pump is the fact that during the repeated up and down strokes, the displacement piston is unable to pump the materials to the mixing gun at constant pressure. Additionally, such pneumatic type displacement piston pumps used in the typical foam applicating situation require large and numerous air compressors, which in turn, involve additional costs as well as the improper use of significant amounts of air. Furthermore, in an effort to overcome variations in pumping pressure, some users have resorted to additional expensive equipment having pressure equalizer chambers. However, notwithstanding these improvements, it was still not possible for a user to adjust the material pressures.
Accordingly, it will be appreciated that foam applicating systems employing such pumping devices suffered from several rather significant disadvantages.
Another prior art approach to on-site foam application systems employs a pair of electric "single diaphragm" pumps simultaneously driven by an electrically driven common prime mover for pumping the foam material constituents to a foam gun. This arrangement also has certain disadvantages. For example, the type of electrically driven diaphragm pump necessary to effectively pump the curable synthetic resin and foaming agent over relatively long distances is complicated in structure and operation. In addition, with known electric diaphragm pumps used for pumping the material, there exists a requirement for an auxiliary pressure chamber for purposes of attempting to avoid pressure fluctuations during pumping. These types of pressure chambers must also be pressurized in attempting to maintain consistent pressure throughout the typical working operation of the pump.
By virtue of the large sizes and complexities of the electric diaphragm pumps, a correspondingly large electric motor is needed to drive both pumps. Further, with relatively large electric motors, it is necessary to use special electrical power sources, thus preventing the use of standard 110 volt electrical outlets. Thus, the motor must be supplied with adequate current from the outside power lines and the attendant equipment, time, costs and labor involved for utilizing such equipment and systems are accordingly increased.
Another problem results from the fact that such motors require more electrical power, thereby rendering them more expensive. Moreover, the pump and associated equipment has such a complicated construction that there is an increased tendency for it to function improperly during normal customary use.
In addition to the foregoing deficiencies in the electric diaphragm pump system, it has nevertheless been determined that such undesirable pressure variations do actually exist in such systems. While not as severe as those encountered with other known systems, nonetheless the pressure fluctuations encountered are of sufficient dimensions to cause inconsistencies and deficiencies in the final foam product similar to those previously described.
Certain other prior art systems utilize belt driven pumps for delivering the constituent materials, a system which not only caused severe power losses, but which resulted in the classical inconsistencies and inaccuracies in the material flows which have been responsible for the production of inferior foam materials.
In general, with all of the above systems, additional problems were encountered with cold temperatures, particularly below about 55.degree. F., since the materials become more viscous and did not flow freely or evenly. Thus, under cold temperature conditions, greater pressures were normally required and pressure fluctuations--as well as their adverse results--were magnified. I have invented a system for the ultimate production of foam materials of the type mentioned, which is not only simple, economical and trouble free, but which provides the requisite foam consistency and uniformity while avoiding the disadvantages of the prior art.